#include <iostream>
#include <fstream>
using namespace std;
fstream f("flip.in",ios::in);
fstream g("flip.out",ios::out);
int i,j,n,m,a[16][16];
int citire(int &n,int &m,int a[][16])
{
f>>n>>m;
   for(i=1;i<=n;i++)
    for(j=1;j<=m;j++)
   f>>a[i][j];
   return 0;}
int verificare(int n,int m,int a[][16])
{int s=0,s1=0;
    //verificare linii
   for(i=1;i<=n;i++)
   {s=0; s1=0;
    for(j=1;j<=m;j++)
    s=s+a[i][j];
   if(s<0)
    {for(j=1;j<=m;j++)
    {a[i][j]=-a[i][j];
    s1=s1+a[i][j];}
    if(s1<s)
    for(j=1;j<=m;j++)
    a[i][j]=-a[i][j];}}
//verificare coloane
    for(j=1;j<=n;j++)
    {s=0; s1=0;
    for(i=1;i<=n;i++)
    s=s+a[i][j];
    if(s<0)
    {for(i=1;i<=n;i++)
    {a[i][j]=-a[i][j];
    s1=s1+a[i][j];}
    if(s1<s)
    for(i=1;i<=n;i++)
    a[i][j]=-a[i][j];}}

return 0;}
int suma(int n,int m,int a[][16])
{int s=0;
    for(i=1;i<=n;i++)
        for(j=1;j<=m;j++)
        s=s+a[i][j];
    return s;
}
int main()
{
    citire(n,m,a);
    verificare(n,m,a);
    g<<suma(n,m,a);
    g.close();
    return 0;
}